[Haskell-cafe] Cabal and more than one version
duncan.coutts at worc.ox.ac.uk
Tue Nov 18 16:30:05 EST 2008
On Tue, 2008-11-18 at 01:48 -0800, Jason Dusek wrote:
> I'd like to be able to do something like:
> if (template-haskell < 2.3)
> cpp-options: -D TH_THE_YOUNGER
> cpp-options: -D TH_THE_ELDER
> I guess this kind of thing is not possible at present?
It is possible, in two different ways.
The easiest way is that if you're using Cabal-1.6 then it provides cpp
macros to test the version number of packages you're using.
The alternative that works back to Cabal-1.2 is to use:
build-depends: template-haskell >= 2.3
cpp-options: -D TH_THE_ELDER
build-depends: template-haskell < 2.3
cpp-options: -D TH_THE_YOUNGER
See also ticket http://hackage.haskell.org/trac/hackage/ticket/209 for a
proposal to add syntactic sugar similar to the syntax you first
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